The present invention relates generally to improved chewing gum compositions including improved carbohydrate syrup compositions and methods of preparation of the chewing gum compositions.
The use of carbohydrate syrups in chewing gums is well known in the art. In particular, relatively low D.E. (dextrose equivalent) carbohydrate syrups are especially desirable for the texture and binding effects which the solids in such syrups provide in certain applications.
However, it has been found that relatively high levels of moisture present in typical carbohydrate syrups have proven unsatisfactory for various reasons. For example, conventional chewing gum has been generally thought to require a moisture content of approximately 3 to 5 percent by weight for aceptable softness and flexibility. Nearly all of the moisture in chewing gum is provided by carbohydrate syrups such as conventional corn syrups or sugar alcohol syrups (including sorbitol solutions and hydrogenated starch hydrolysate solutions) typically added to chewing gum compositions to improve binding and softness characteristics in the gum. A major problem with conventional gum compositions is that they gradually become hard and brittle from moisture loss which occurs when the chewing gum is stored at a relative humidity lower than the equilibrium relative humidity of the gum. When moisture is lost from the gum, ingredients originally dissolved in the water recrystallize, causing the gum to become stiff and brittle. For this reason, chewing gum is typically wrapped in moisture-impermeable packages to prevent loss of moisture. However, even with such packaging, the moisture may eventually migrate out of the gum.
In sugarless chewing gums, hydrogenated starch hydrolysates and sugar alcohols such as sorbitol are often used as sweeteners and bulking agents. Such sugarless gums are hygroscopic in nature, attracting moisture from the atmosphere. The result is that, over time, sugarless gums often become "sticky" and loose their body and texture. It is desirable to use relatively low-moisture formulations including low-moisture carbohydrate syrups in such gums so that the gums will be able to withstand greater moisture absorption before they reach an undesirably "sticky" state.
In sugarless gums, it is sometimes advantageous to use hydrogenated starch hydrolysate solutions rather than sorbitol solutions because of the greater binding effects of the higher molecular weight components in the hydrogenated starch hydrolysates solids. However, hydrogenated starch hydrolysate syrups typically have a relatively high moisture level. The reduction of the amount of moisture in such syrups allows more hydrogenated starch hydrolysates to be used without exceeding moisture limitations in the final chewing gum products.
Furthermore, it has been found desirable to minimize the moisture content of chewing gum compositions in order to prevent the deterioration of certain moisture-sensitive ingredients. For example, it is well known that the stability of artificial dipeptide sweeteners such as aspartame (L-spartyl-L-phenylalanine methyl ester) in chewing gums is a function of water activity, time, temperature and pH. In aqueous systems, aspartame spontaneously converts to diketopiperazine with proportional loss of sweetness. The rate of this conversion reaction can be controlled by minimizing the water activity in chewing gums containing aspartame.
These and other undesirable effects of relatively high moisture levels in chewing gums containing carbohydrate syrup compositions can be minimized by reducing or evaporating moisture from the carbohydrate syrups. However, problems have been encountered in economically evaporating moisture initially present in certain carbohydrate syrup compositions, particularly low D.E. carbohydrate syrups, to desired relatively low levels. Specifically, as such syrups are evaporated, their viscosities increase substantially, with the result that at some moisture levels the syrups cannot be economically processed in conventional evaporating equipment. Furthermore, even when evaporation to a desired moisture content is possible, further handling of the syrup, especially if it is cooled after evaporation, is difficult if not impossible. Thus, the syrup must be kept hot to facilitate handling and used quickly to prevent degradation by the heat. If the syrup is cooled, the extreme viscosity makes reheating it a slow and difficult process.